Arjan van de Ven wrote:
>On Sat, 2002-10-26 at 21:22, Manfred Spraul wrote:
>
>
>>kmalloc spends a large part of the total execution time trying to find
>>the cache for the passed in size.
>>
>>
>
>would it be possible for fixed size kmalloc's to have the compiler
>precalculate this ?
>
>
>
>
My patch is attached.
Question to the preprocessor experts:
is there a simpler way to achieve that? Right now the list of kmalloc
caches exists in 3 copies, which could easily get out of sync.
--
Manfred
// $Header$ // Kernel Version: // VERSION = 2 // PATCHLEVEL = 5 // SUBLEVEL = 45 // EXTRAVERSION = --- 2.5/include/linux/slab.h Sat Oct 26 21:02:12 2002 +++ build-2.5/include/linux/slab.h Thu Oct 31 23:58:26 2002 @@ -58,7 +58,80 @@ extern void kmem_cache_free(kmem_cache_t *, void *); extern unsigned int kmem_cache_size(kmem_cache_t *); -extern void *kmalloc(size_t, int); +/* Size description struct for general caches. */ +struct cache_sizes { + size_t cs_size; + kmem_cache_t *cs_cachep; + kmem_cache_t *cs_dmacachep; +}; +extern struct cache_sizes malloc_sizes[]; +extern void __you_cannot_kmalloc_more_than_128_kilo_bytes(void); + +enum malloc_numbers +{ +#if PAGE_SIZE == 4096 + kmalloc_size_32 = 0, +#endif + kmalloc_size_64, +#if L1_CACHE_BYTES < 64 + kmalloc_size_96, +#endif + kmalloc_size_128, +#if L1_CACHE_BYTES < 128 + kmalloc_size_192, +#endif + kmalloc_size_256, + kmalloc_size_512, + kmalloc_size_1024, + kmalloc_size_2048, + kmalloc_size_4096, + kmalloc_size_8192, + kmalloc_size_16384, + kmalloc_size_32768, + kmalloc_size_65536, + kmalloc_size_131072 +}; + +static inline void* __constant_kmalloc(size_t size, int flags) +{ +#define FIXED_ALLOC(len) \ + if(size <= len) \ + return kmem_cache_alloc( (flags & GFP_DMA)? \ + malloc_sizes[kmalloc_size_##len].cs_dmacachep \ + : malloc_sizes[kmalloc_size_##len].cs_cachep, \ + flags) +#if PAGE_SIZE == 4096 + FIXED_ALLOC(32); +#endif + FIXED_ALLOC(64); +#if L1_CACHE_BYTES < 64 + FIXED_ALLOC(96); +#endif + FIXED_ALLOC(128); +#if L1_CACHE_BYTES < 128 + FIXED_ALLOC(192); +#endif + FIXED_ALLOC(256); + FIXED_ALLOC(512); + FIXED_ALLOC(1024); + FIXED_ALLOC(2048); + FIXED_ALLOC(4096); + FIXED_ALLOC(8192); + FIXED_ALLOC(16384); + FIXED_ALLOC(32768); + FIXED_ALLOC(65536); + FIXED_ALLOC(131072); +#undef FIXED_ALLOC + __you_cannot_kmalloc_more_than_128_kilo_bytes(); + return NULL; +} +extern void *__kmalloc(size_t, int); + +#define kmalloc(size, flags) \ + (__builtin_constant_p(size) ? \ + __constant_kmalloc((size),(flags)) : \ + __kmalloc(size,flags)) + extern void kfree(const void *); extern int FASTCALL(kmem_cache_reap(int)); --- 2.5/mm/slab.c Thu Oct 31 18:48:19 2002 +++ build-2.5/mm/slab.c Thu Oct 31 23:58:26 2002 @@ -369,15 +369,8 @@ #define SET_PAGE_SLAB(pg,x) ((pg)->list.prev = (struct list_head *)(x)) #define GET_PAGE_SLAB(pg) ((struct slab *)(pg)->list.prev) -/* Size description struct for general caches. */ -struct cache_sizes { - size_t cs_size; - kmem_cache_t *cs_cachep; - kmem_cache_t *cs_dmacachep; -}; - /* These are the default caches for kmalloc. Custom caches can have other sizes. */ -static struct cache_sizes malloc_sizes[] = { +struct cache_sizes malloc_sizes[] = { #if PAGE_SIZE == 4096 { 32, NULL, NULL}, #endif @@ -1804,7 +1797,7 @@ * platforms. For example, on i386, it means that the memory must come * from the first 16MB. */ -void * kmalloc (size_t size, int flags) +void * __kmalloc (size_t size, int flags) { struct cache_sizes *csizep = malloc_sizes; --- 2.5/kernel/ksyms.c Thu Oct 31 18:48:18 2002 +++ build-2.5/kernel/ksyms.c Thu Oct 31 23:44:54 2002 @@ -102,7 +102,8 @@ EXPORT_SYMBOL(kmem_cache_size); EXPORT_SYMBOL(set_shrinker); EXPORT_SYMBOL(remove_shrinker); -EXPORT_SYMBOL(kmalloc); +EXPORT_SYMBOL(malloc_sizes); +EXPORT_SYMBOL(__kmalloc); EXPORT_SYMBOL(kfree); EXPORT_SYMBOL(vfree); EXPORT_SYMBOL(__vmalloc);
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